The evolution and collision of dark solitary waves (solitons) appearing in cigar-shaped Bose-Einstein condensates with repulsive atom-atom interaction are here considered using a Boussinesq-Korteweg–de Vries description. We provide theoretical predictions and computer experiment evidence about their phase shifts or change of trajectories, in the space-time plot, corresponding upon collisions. Details are also given about a suggested experiment that could assess their genuine solitonic nature.

• Received 19 May 2000

DOI:https://doi.org/10.1103/PhysRevA.64.013617